The present invention refers to a locking device intended as a fastening means for prostheses, such as leg- and arm prostheses, of the kind where the prosthesis is to be fastened to a cylindrical part such as a pin, an axle, a tube or the like. It can for example be used in such cases where a silicone stocking is applied on the leg- or arm stump, said stocking having a plastic cup moulded into the bottom thereof and said cup having a pin attached thereto. The leg- and arm stump provided with a silicone stocking is passed into a prosthesis sleeve connected to the prosthesis, said prosthesis sleeve is provided with a locking device for the pin.
In the international patent application WO 94/04101 it is shown a fastening means intended for a prosthesis, said fastening means comprises a tilted washer, which by spring force is kept in tilted position and by this is locked to the pin. The degree of tilting of the washer can be reduced by means of an actuating means by which the locking to the pin can be released.
In DE-C-1,097,217 there is shown a clamping device for axles and tubes and which comprises a ring of balls arranged in a cage, which by means of spring action is pressed into a conical seat, at which the locking device is locked to the axle in axial direction, said clamping device further comprises actuating means for releasing the ring of balls from the conical seat. The actuating means comprises a fork-shaped member which grips the pin and which is provided with inclined surfaces cooperating with inclined surfaces on a holding-on ring, so that the holder-on ring and the ring of balls by wedge action is displaced along the pin. There is no indication that this clamping device would be intended to be used in connection with prostheses. Besides it is designed so that the axle only may be passed into the locking device in a completely straight position.
The object of the present invention is to provide a locking device of the kind mentioned above, which should be positionable in a stepless way, it should permit rotation around the pin also in locked position, it should be relatively insensitive to dirt and threads from textiles which easily may penetrate into it, it should permit the pin to be easily inserted into it also in a slightly oblique position and it should lock from movement out of the locking mechanism in a stepless way.
The locking device according to the invention is characterized by the fact that it comprises a cage with a ring of balls arranged therein, said ring of balls by means of spring action is pressed into a conical seat in the cage, at which the locking device is locked to the pin or the like in axial direction while rotational movement is admitted, said locking device further comprises actuating means for releasing the ring of balls from the conical seat, at which the cage is arranged in a housing provided with a through opening for receiving said pin or the like, said opening has a larger diameter than the pin or the like in order to admit this to be inserted also in an oblique position.